Isoprene, which is found in natural rubber, is also employed to produce synthetic polymers including polyisoprene and various isoprene-based rubbery copolymers such as styrene-butadiene type copolymers. Isoprene can be recovered as a byproduct of various refining operations or it can be produced by the dehydrogenation of isoamylene which can be in thermodynamic equilibrium with other methyl butene isomers, 2-methyl 1-butene and 3-methyl 1-butene.
Isoprene containing rubber products include cis- and trans-polyisoprenes, and copolymers of isoprene and of monomers such as styrene, butadiene, isobutylene and acrylonitrate. Such products can be produced by any suitable techniques employing commercial initiators and polymerization catalysts. For example, polyisoprene may be polymerized in the presence of a coordination catalyst based upon a titanium tetrachloride with a trialkyl aluminum co-catalyst, such as triethyl aluminum. The titanium tetrachloride catalyst may be combined with either ferric or vanadium trichloride to produce a polymer having a 97% trans 1, 4 microstructure. Various other isoprene containing polymers and co-polymers may be produced employing catalyst-initiator systems which are well known skilled in the art.